Evaporation loss determination apparatus and method



Jan. 2, 1968 J. B. CHRISTIAN EVAPORATION LOSS DETERMINATION APPARATUS AND METHOD 3 Sheets-Sheet 1 Filed April 1, 1965 w km fw m mm M Winn? 4 9. W M 0. d W W w Jan.2,1968 J. B. CHRISTIAN, 3,360,985

EVAPORATION LOSS DETERMINATION APPARATUS AND METHOD Filed April 1, 1965 i s Sheets-Sheet 2 INVENTOR. 4/ 49. 6/09/5770 Jan. 2, 1968 J, cHR|sT|AN 3,360,985

EVAPORATION LOSS DETERMINATION APPARATUS AND METHOD Filed April 1, 1965 s Sheets-Sheet 5 JO 40v 8 c MEI/S7719 rro elvr s United States Patent M 3,360,985 EVAPORATION LOSS DETERMINATION APPARATUS AND METHOD John B. Christian, Yellow Springs, Ohio, assignor to the United States of America, as represented by the Secretary of the Air Force Filed Apr. 1, 1965, Ser. No. 444,876 9 Claims. (CI. 7353) ABSTRACT OF THE DISCLOSURE The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without the payment to me of any royalty thereon.

This invention concerns an apparatus and a method for making accurate determinations of vaporization losses from materials such as liquids, semisolids, and the like,

of which oils and greases may be taken as being illustrative examples.

Air and space vehicles of the present time are demanding increasingly wide temperature range performance of lubricants whether the lubricants are to be used in mechanical devices, instruments, or other equipment. Future air and space craft may be expected to require lubricants which do not lose their lubricating,characteristics over wider temperature ranges than have been satisfactory heretofore.

These technological advancements have dictated re- I search and development programs involving lubricants that at room temperature are liquids, such as oils; that are semisolids, such as greases; that may or may not contain solids such as powdered graphite, and the like. In

meeting the demand for lubricants having increasingly wide temperature ranges over which they are required to continuously perform their lubricating services, it has become increasingly necessary to design new and improved research tools and test procedures to meet these needs.

Important properties of a lubricant may be taken as volatility and evaporation characteristics as in oils and greases, over the range of temperatures through which lubrication is required. Earlier lubricants that have served adequately over ranges in temperature with an upper limit of 350 P. which is 177 C are inadequate as the temperature range upper limit approaches 1,000 P. which is 538 C. r

The need described above has resulted in accelerated investigations in research tools and test methods investigating the surface tensions and vapor pressures and related properties of fluids, oils, greases, and related materials, over increaseingly wide temperature ranges. These etforts have resulted in a testmanual that has been made available to testing laboratories and to lubricant researchers and manufacturers and the apparatus and processes disclosed in the manual are now being considered by The American Society for Testing Materials.

The objects of the present invention are to provide a new and useful apparatus and method for determining accurately under controlled conditions of temperature,

Patented Jan. 2, 1968 pressure atmosphere, the vaporization characteristics of materials.

In the accompanying drawings are shown successfully operative illustrative embodiments of the present invention.

In the drawings:

FIG. 1 is a plan view of a six-cell evaporation tester of controlled atmosphere, temperature, and pressure that embodies the present invention;

FIG. 2 is an enlarged fragmentary sectional View taken about on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional view of a grease cup replacement for the oil cup in FIG. 2; and

FIG. 4 is an air flow pattern applicable to the process that is disclosed herein.

In the accompanying drawings, the evaporation loss determination apparatus in FIG. 1 comprises a desired plurality of the cells 1 in the block 2 maintained at a temperature by heaters 3 and 4 controlled preferably by a Capaciline Model 660A auxiliary heater control and a Wheelco temperature control, both manufactured by Wheelco Instruments Division, Barber-Coleman Company, Rockford, Ill. The heaters 3 and 4 are disposed inwardly of insulation 5 secured within a steel frame 6, lifted by handles 7, 7', etc., and attached by bolts 8, 8', etc. A top 9 is apertured at 13, 13, etc., through which apertures the exhaust vapors escape and the sample cups are changed.

Air, an inert gas, or the like, is supplied to the cells 1 through a pipe 10 from which laterals 11, 11', etc., are taken off to continue spirally around each cell and to enter the cell through the bottom thereof as indicated in FIG. 2. The cells 1 are hollow and may be of a desired section such as cylindrical, rectangular, or of other shapes as preferred. The described structure assures the temperature of the air or gas to have arrived at the temperature of the block before it is admitted into the bottom end of the cell. The hot junctions of a plurality of the thermocouples 12, 12', etc., are positioned between the cells in the block 2 and serve to indicate accurately temperature control of the apparatus.

Each of the cells 1 is closed from above by a cover 15 that is removably attached in place by suitable means such as by screws 16, or the like. Each cover supports the upper end of an eduction tube 17 that is welded, threaded, or otherwise secured to both the cover and to a grommet 18 type of cap for the tube. The lower end of the eduction tube 17 supports the sample to be tested Within the cell 1.

In FIG. 2 of the drawings, the lower end of the eduction tube makes threaded engagement with the oil hood 20 to which the oil sample receiving cup 21 makes threaded engagement in a manner that is removable and replaceable by the grease hood 22 in FIG. 3., to which the grease sample receiving cup 23 is removably attached. The oil cup 21 is adequately deep to eliminate oil splashings. The grease cup 23 is relatively shallow with a flat upper edge 26 such that upon filling the cup with grease and entrapping no air pockets, the upper surface of the grease is made fiat by passing a straight knife edge across the top edge of the cup, making certain that all grease to be tested remains within the cup. Provision is made for the steady flow of air across the oil in the oil cup 21 by a desired plurality of oil cup wall apertures 24. Air passing through the apertures 24 passes from the periphery of the oil cup 21 to enter the lower end of the eduction tube 17 and up the tube through its cap 13 into the ambient atmosphere. In a similar manner, a desired plurality of grease hood apertures 25 assure the steady flow of air across the grease in the grease cup 23.

The operation of the apparatus, as disclosed herein, is presented diagrammatically in FIG. 4 of the drawings.

In FIG. 4, air or other gas that is fed to the intake 30 passes into the air pressure regulator 31 where it is subjected to a predetermined pressure that is adequate to carry the air through the system. The air pressurized in the regulator 31 is passed as indicated by arrows, to a preferred dryer '32, such as the dessicant containing air dryer Gilbarco that is marketed by the Gilbert and Barker Manufacturing Company, West Springfield, Mass. The air may be further processed by being passed through the auxiliary air dryer 33 and then passed through flow rate indicating pressure meters 34, 34, etc., to the block 2. The block 2 is heated by the heaters 3 and 4 and the air then passes spirally around the cells 1, near the bottom of which cells the air is delivered as indicated in FIG. 2, at a temperature regulated from outside the assembly that is indicated by the thermocouples 12, 12, etc., preferably by the Capaciline Model 660A and the Wh-eelco temperature controller mentioned above.

The temperature control of the block 2 indicated by the thermocouples 12, 12, etc. determines the temperature of samples in the oil cup 21 or in the grease cup 23, Whichever is attached to the lower end of the eduction tube. Evaporation loss by the sample is the weight difference at a predetermined temperature between the sample before and after air or other gas flow across its exposed surface has continued for a predetermined period of time during which the sample undergoes a vaporization loss transferred from the sample to the atmosphere.

The process steps for determining the evaporation loss of a material such as a fluid oil or a semisolid grease is accomplished by Weighing the sample container in its clean and dry condition, introducing a sample of the material into the container, Weighing the container and the sample together for the difference weight of the sample alone at the start of the run, attaching the sample bearing container to the lower end of the eduction tube by securely interengaging the threaded areas thereof, adjusting the cell temperature at a predetermined value, causing a gas to flow from apertures in the edge of the sample container to centrally thereof and up the eduction tube for a predetermined period of time for removing vapor from the surface of the sample, releasing the sample container from its attachment with the eduction tube, and on weighing the sample container with the residual sample therein for deriving the weight of the vapor removed by the gas flow from the original sample.

It is to be understood that the apparatus and the process that are described herein are submitted as being illustrative of the present invention and that limited modifications may be made therein without departing from the spirit and the scope of the present invention.

I claim:

1. The evaporation loss determination apparatus comprising a hollow cell, gas conducting means positioned spirally around the cell and discharging gas into the bottom of the cell, heater means maintaining the cell and the gas conducting means at a predetermined temperature, a cell cover at the upper end of the cell, an eduction tube suspended by the cover into the cell and terminating in a distal end remote from its attached end, and an evaporation loss sample cup removably attached to the distal end of the eduction tube within the cell and positioned to receive air flow substantially from its periphery against and across the surface of a sample within the cup to centrally of the sample and to vent the air upwardly of the eduction tube.

2. The apparatus defined by claim 1 inclusive of a top that is apertured for the change of sample cups in the cell.

3. The apparatus defined by claim 1 wherein the distal end of the eduction tube is threaded, and a plurality of evaporation loss sample cups supported within the cell by means removably engaging the threaded end of the reduction tube.

4. The apparatus defined in claim 3 inclusive of hood members interposed between and releasably secured to the threaded end of the eduction tube and the sample cup and serving in directing air flow entering peripherally of the sample cup axially downwardly against the surface of the sample.

5. The evaporation loss determination apparatus comprising a hollow cylindrical cell having an open end for access to the interior of the cell, a cover removably positioned on the open end of the cell, an eduction tube supported by the cover for being dependent within the cell and terminating within the cell in an open end, a hood removably securable on the open end of the eduction tube within the cell, and a sample cup removably secur- :able to the hood and to which cup an atmosphere within the cell has access.

6. The apparatus defined by claim 5 wherein the sample cup is threaded internally adjacent its upper edge for removably engaging external threads on the hood.

7. The apparatus defined by claim 5 wherein the sample cup is threaded externally adjacent its upper edge for removably engaging the internal threads adjacent the lower edge of the hood.

8. The process for determining an evaporation loss from an oil sample by weighing an oil sample cup, introducing a sample of oil into the sample cup, weighing the sample cup containing the oil for the difference weight of the -oil sample, attaching an oil hood to the sample cup,

attaching the oil hood to an eduction tube Within a cell, maintaining the oil sample at a predetermined temperature, causing a gas to flow from the periphery of the sample exposed surface to centrally thereof and substantially over the surface of the oil sample for a predetermined period of time for removing vapor from the oil sample, and weighing the sample cup with a residual oil sample therein for deriving the weight of the vapor removed by the gas fiow from the original oil sample.

9. The process for determining an evaporation loss from a grease sample by weighing a grease sample cup, introducing a sample of grease into the sample cup, weighing the sample cup containing the grease for the dilference weight of the grease sample, attaching a grease hood to the sample cup, attaching the grease hood to an eduction tube within a cell, maintaining the grease sample at a predetermined temperature, causing a gas to flow from around the edge of the sample to centrally thereof and substantially over the surface of the grease sample for a predetermined period of time for removing vapor from the grease sample and the vapor laden gas to be drawn upwardly from centrally of the sample surface, and weighing the sample cup with a residual grease sample therein for obtaining the weight of the vapor removed by the gas flow from the original grease sample.

References Cited UNITED STATES PATENTS 8/1920 Spencer. 4/1954 Ekelund 73-76 XR DAVID SCHONBERG, Primary Examiner. 

